Communication partner appliance with automatic send mode activation

ABSTRACT

A communication partner appliance is implemented within a near field communication system. The communication partner appliance includes a receiver, a detector, and a processor. The receiver receives a NFC command signal from another communication partner appliance. The detector detects whether a carrier signal from the other communication partner appliance is present at the receiver at a time other than during a transmission of the NFC command signal from the other communication partner appliance to the receiver. The processor controls a power supply element based on a determination by the detector whether the carrier signal from the other communication partner appliance is present at the receiver. The power supply element is configured to establish a connection to either a first power supply or a second power supply. The first power supply is dependent on the carrier signal, and the second power supply is independent of the carrier signal.

This application is a Continuation of U.S. application Ser. No.13/553,675 filed on Jul. 19, 2012, entitled “Communication partnerappliance with automatic send mode activation,” which is a Continuationof U.S. application Ser. No. 13/405,778 filed on Feb. 27, 2012, entitled“Communication partner appliance with automatic send mode activation,”which is a Continuation of U.S. application Ser. No. 13/250,060 filed onSep. 30, 2011, now U.S. Pat. No. 8,150,316, entitled “Communicationpartner appliance with automatic send mode activation,” which is aContinuation of U.S. application Ser. No. 10/577,516 filed on Apr. 26,2006, now U.S. Pat. No. 8,060,010, entitled “Communication partnerappliance with automatic send mode activation,” which claims priority toPCT Application No. PCT/IB04/52231 filed on Oct. 28, 2004, which claimspriority to EP Application No. 03104010.8 filed on Oct. 29, 2003, eachof which is incorporated by reference herein in its entirety.

The invention relates to a circuit, this circuit being provided for acommunication partner appliance that is designed for contact lesscommunication, this communication partner appliance being provided for acommunication system with at least one further communication partnerappliance, in which circuit a first communication mode or a secondcommunication mode can be activated.

The invention furthermore relates to a communication partner appliancethat is designed as a data carrier and contains a circuit as describedabove in the first paragraph.

The invention furthermore relates to a circuit, this circuit beingprovided for a communication partner appliance that is designed forcontact less communication, this communication partner appliance beingprovided for a communication system with at least one furthercommunication partner appliance, this circuit containing the meanslisted below: production means for producing a carrier signal andtransmission means for transmitting the carrier signal to the furthercommunication partner appliance.

The invention furthermore relates to a communication partner appliancethat is designed as a communication station and includes a circuit asdescribed above in the third paragraph.

The invention furthermore relates to a method of activating a firstcommunication mode or a second communication mode of a communicationpartner appliance, wherein the communication partner appliance isprovided for a communication system with at least one furthercommunication partner appliance, and wherein a carrier signal istransmitted by the at least one further communication partner appliance,this carrier signal being received with the communication partnerappliance.

Such a circuit of the type described in the first paragraph above, andsuch a communication partner appliance of the type described at theoutset in the second paragraph, which has such a circuit, and such amethod, are known from the patent document U.S. Pat. No. 6,466,771. Inan embodiment, the known document discloses a transponder with acircuit, with the transponder and/or the circuit being designed so as tobe capable of being switched over, namely between a passivecommunication mode and an active communication mode. It is also knownfrom the document that the further communication partner appliance isdesigned as a reader station or communication station for transmitting acarrier signal.

In the case of the transponder, in the case of the active communicationmode a power supply for the circuit is provided that is independent ofthe carrier signal, and in the case of the passive communication mode apower supply for the circuit is provided, which power supply isdependent on the carrier signal in a known manner. The known transponderor the known circuit has command signal recognition means forrecognizing and processing command signals, these command signals beinggenerated in the further communication partner appliance and beingtransmitted with the aid of the carrier signal. Switching over betweenthe passive communication mode and the active communication mode takesplace through a special command signal which is transmitted by thefurther communication partner appliance and which is designed as achange-over command signal.

A disadvantage in the case of this known transponder and method is thata desired flexibility of deployment or usability in other communicationsystems is subject to limits or is not possible, for example in thosecommunication systems in which the reader station cannot generate ortransmit a change-over command signal.

A further disadvantage is that a relatively large and complicated andtherefore error-prone control arrangement is required, and in fact inboth the transponder and in the reader station.

It is an object of the invention to eliminate the disadvantagesmentioned above, and to realize an improved method and an improvedcircuit for a communication partner appliance designed as a datacarrier, and an improved communication partner appliance designed as adata carrier, and an improved circuit for a communication partnerappliance designed as a communication station, and an improvedcommunication partner appliance designed as a communication station.

In one embodiment, a communication partner appliance is implementedwithin a near field communication system. The communication partnerappliance includes a receiver, a detector, and a processor. The receiverreceives a NFC command signal from another communication partnerappliance. The detector detects whether a carrier signal from the othercommunication partner appliance is present at the receiver at a timeother than during a transmission of the NFC command signal from theother communication partner appliance to the receiver. The processorcontrols a power supply element based on a determination by the detectorwhether the carrier signal from the other communication partnerappliance is present at the receiver. The power supply element isconfigured to establish a connection to either a first power supply or asecond power supply. The first power supply is dependent on the carriersignal, and the second power supply is independent of the carriersignal.

In another embodiment, the communication partner appliance includes atransmitter and a processor. The transmitter transmits a near-fieldcommunication (NFC) command signal to another communication partnerappliance according to an active communication mode. The command signalincludes a request for data from the other communication partnerappliance. The processor switches from the active communication mode toa passive communication mode in response to a determination that theresponse signal is not received from the other communication partnerappliance. Other embodiments of the communication partner appliance arealso described.

In another embodiment, a method includes making a determination at afirst communication partner appliance whether a carrier signal from asecond communication partner appliance is present at the firstcommunication partner appliance at a time other than during atransmission of a near-field communication (NFC) command signal from thesecond communication partner appliance to the first communicationpartner appliance. The method also includes controlling a power supplyelement of the first communication partner appliance based on thedetermination whether the carrier signal from the second communicationpartner appliance is present at the first communication partnerappliance. The power supply element is configured to establish aconnection to either a first power supply or a second power supply. Thefirst power supply is dependent on the carrier signal. The second powersupply is independent of the carrier signal. Other embodiments of themethod are also described.

In other embodiments, to achieve the object stated above, in the case ofa circuit for a communication partner appliance which is designed asdata carrier and which is in accordance with the invention, features inaccordance with the invention are provided, so that such a circuitaccording to the invention can be characterized in the following manner,namely:

A circuit, this circuit being provided for a communication partnerappliance that is designed for contact less communication and as a datacarrier, this communication partner appliance being provided for acommunication system with at least one further communication partnerappliance, in which circuit a first communication mode or a secondcommunication mode can be activated, and which circuit has the meanslisted below:

activators for activating the first communication mode or the secondcommunication mode, and reception means for receiving a carrier signalthat is transmitted by the at least one further communication partnerappliance, and detectors for detecting the presence of the receivedcarrier signal, these detectors transmitting a carrier signal presentsignal in the event that the carrier signal is present, and otherwisetransmitting a carrier signal not-present signal, and command signalrecognition means for recognizing a command signal that can betransmitted with the aid of the carrier signal and for transmitting acommand-end signal that represents the end of the transmitted commandsignal, and determination means for determining whether, after theoccurrence of the command-end signal, at a given measurement point intime, the carrier signal present signal is present, with whichdetermination means a first activation signal can be transmitted whenthe carrier signal present signal is present, and otherwise a secondactivation signal can be transmitted, with which first activation signalthe circuit can be brought into the first communication mode with theaid of the activators, and with which second activation signal thecircuit can be brought into the second communication mode with the aidof the activators.

To achieve the object stated above, furthermore in the case of acommunication partner appliance according to the invention, which isdesigned as a data carrier, features according to the invention areprovided, so that such a communication partner appliance according tothe invention can be characterized in the following manner, namely:

A communication partner appliance that is designed as a data carrier andis equipped with a circuit.

To achieve the object stated above, furthermore in the case of a circuitfor a communication partner appliance according to the invention that isdesigned as a communication station, features according to the inventionare provided, so that such a circuit according to the invention can becharacterized in the following manner, namely:

A circuit, this circuit being provided for a communication partnerappliance that is designed for contact less communication and as acommunication station, this communication partner appliance beingprovided for a communication system with at least one furthercommunication partner appliance, in which further communication partnerappliance a first communication mode or a second communication mode canbe activated, this circuit containing the means listed below:

production means for producing a carrier signal, and transmission meansfor transmitting the carrier signal to the further communication partnerappliance, and

arranging means for arranging a communication mode, and a generator forgenerating at least one command signal, which command signal can betransmitted to the further communication partner appliance with the aidof the carrier signal, and

first control elements for transmitting a command-end signal thatrepresents the end of the generated command signal, and second controlelements with which second control elements, after the occurrence of thecommand-end signal, the generation and/or transmission of the carriersignal can be ended at a particular point in time.

To achieve the object stated above, furthermore in the case of acommunication partner appliance according to the invention that isdesigned as a communication station, features according to the inventionare provided so that such a communication partner appliance according tothe invention can be characterized in the following manner, namely:

A communication partner appliance that is designed as a communicationstation and is equipped with a circuit.

To achieve the object stated above, in the case of a method according tothe invention, features according to the invention are provided, suchthat a method according to the invention can be characterized in thefollowing manner, namely:

A method for activating a first communication mode or a secondcommunication mode of a communication partner appliance, wherein thecommunication partner appliance is provided for a communication systemwith at least one further communication partner appliance, and wherein acarrier signal is transmitted by the at least one further communicationpartner appliance, this carrier signal being received with thecommunication partner appliance, and

wherein in the communication partner appliance, detection of thepresence of the received carrier signal takes place, and in the event ofthe carrier signal being present, a carrier signal present signal istransmitted, and otherwise a carrier signal not-present signal, andwherein recognition of a command signal that can be transmitted with theaid of the carrier signal takes place, and the transmission of acommand-end signal that represents the end of the transmitted commandsignal takes place, and wherein determination is carried out to seewhether, after the occurrence of the command-end signal, at ameasurement point in time, the carrier signal present signal is present,wherein a first activation signal is transmitted when the carrier signalpresent signal is present, and otherwise a second activation signal istransmitted, and wherein with the first activation signal, activation ofthe communication partner appliance into the first communication mode iscarried out, or with the second activation signal an activation of thecommunication partner appliance into the second communication mode iscarried out.

Through the provision of the features according to the invention, it isachieved in an advantageous and easily realized manner that wherecommunication partner appliances are used which, in accordance with theinvention, are designed as a communication station, and which enter intocommunication in a communication system with communication partnerappliances designed as data carriers, the communication partnerappliances designed as data carriers automatically recognize in whichcommunication mode a communication response of the communication partnerappliances designed as data carriers should take place, i.e. for examplewhether the response should be made in an active transmission orcommunication mode, or in a passive transmission or communication mode.Furthermore, on account of the measures according to the invention, anadvantage is achieved in particular where a communication partnerappliance is designed as both a communication station and a datacarrier, through which diverse deployment in various communicationsystems is possible. Thus for example in a so-called “Near FieldCommunication” (NFC) system, two communication partner appliances thatare designed as both a communication station and a data carrier cancommunicate with one another, wherein one of the two communicationpartner appliances is activated as a communication station and exchangesdata with the other communication partner appliance. Such communicationpartner appliances are mostly designed as mobile devices, and have amobile power supply source. As a result of considerations of energyconsumption in the case of such communication partner appliances, itmust be noted that an optimum, energy-saving power supply is achievedwhen both communication partner appliances have their own power supplyactivated during communication. On the other hand, such communicationpartner appliances according to the invention can be used to advantagein, for example, an entry monitoring system, in which entry monitoringsystem an entry-monitoring communication station communicates withcommunication partner appliances which in accordance with the inventionare designed as data carriers, wherein the entry-monitoringcommunication station has a fixed power supply, in other words to acertain extent there is an inexhaustible energy source, and wherein thedata carriers can, advantageously, communicate in the passivecommunication mode, and thus conserve their own energy source, whichenergy source is limited in terms of energy output.

In the case of a communication station according to the invention, thecommunication mode can be arranged by an arranging action that iscarried out by a user or support technician. It has been shown to beparticularly advantageous if, in addition, additional measures areprovided. Through this, automatic switch-over of the communication modecan be carried out, depending on a power supply of the communicationstation.

In the case of a communication station according to the invention, ithas been proven to be advantageous if, in addition, additional measuresare provided. This provides greater flexibility in communication withcommunication partner appliances. For example, in the case where aninquiry is made of a data carrier by the communication station in anactive communication mode, [and] this data carrier does not or cannotemit a response signal because the relevant data carrier has no suitablepower supply of its own for communicating in the active communicationmode or, if there is an energy source, this power supply is no longersufficient, and wherein as a consequence of the missing response signal,the passive communication mode is set in the communication station.

In the case of a communication station according to the invention, ithas been shown to be advantageous if additional measures are provided.Through this, a favorable energy balance of the power supplies of thecommunication partner appliances can be achieved.

These and other aspects of the invention are apparent from and will beelucidated with reference to the embodiments described hereinafter.

The invention will be described in greater detail below, on the basis ofthe embodiments shown in the drawings, to which however the invention isnot restricted.

FIG. 1 shows schematically, in the form of a block diagram, those partsof communication partner appliances according to the invention that areimportant in the present connection, these communication partnerappliances each containing a circuit according to the invention.

FIG. 2 shows a deployment of a communication partner appliance accordingto the invention in an entry-monitoring communication system.

FIG. 3 shows a deployment of a communication partner appliance accordingto the invention in a further communication system.

FIG. 4 shows, schematically, commands and signals that are transmittedbetween the communication partner appliances.

FIG. 1 shows a communication system 1 with communication partnerappliances in a communication area CA, this communication area CA beingindicated by a broken line. In the following, the communication partnerappliances are referred to as devices, for brevity. Here, one device isdesigned as a data carrier 2 and a further device is designed as acommunication station or reader station 3.

The reader station 3 is designed for contact less communication with thedata carrier 2. The data carrier 2 has a circuit 4, in which circuit 4either a first communication mode or a second communication mode can beactivated, which is explained in greater detail below.

In this case, the reader station 3 is a portion of a portable smallcomputer, in other words a PDA, and contains a station circuit 5, thisstation circuit 5 being designed as an integrated circuit and containinga station micro-computer 6. The station micro-computer 6 contains acentral processing unit 7 and station storage media 8, this centralprocessing unit 7 and station storage media 8 working together in afamiliar manner. The station micro-computer 6 is furthermore connectedto a main computer of the PDA, with the aid of interface elements, notshown, and a bus connection, and is designed to communicate with themain computer.

With the aid of the central processing unit 7, arranging means 9 forarranging a communication mode, and generators 10 for generating atleast one command signal, and first control elements 11 for transmittinga command-end signal CES that represents the end of the at least onegenerated command signal, and

second control elements 12 and reception signal processing means 13 andsequence controllers 14 are realized; these items will be dealt with ingreater detail below.

The station circuit 5 furthermore has generating means 15 for generatinga carrier signal RS, and modulation elements 16 and demodulationelements 17. The modulation elements 16 are connected to the generatingmeans 15 and the generators 10, and are designed for modulating thecarrier signal RS with the command signals. Also contained in thestation circuit 5 are encryption elements, not shown, which encryptionelements are arranged before the modulation elements 16, in order tocarry out encryption of the respective command signal before modulation.

The reader station 3 has station transmission means 18, these stationtransmission means 18 forming both transmitters and receivers, and whichdefine the communication area CA in the case of transmission, and whichin the present case are designed with a frequency of 13.56 MHz for thetransmission of a communication station signal or reader signal RS′, andwhich are designed for receiving a data carrier signal TS from the datacarrier 2. Here, the station transmission means 18 are connected to themodulation elements 16 and demodulation elements 17. Such generatingmeans 15, modulation elements 16, demodulation elements 17, stationtransmission means 18 and encryption elements are well known inspecialist circles, for example from the document U.S. Pat. No.5,537,105 A1, the disclosure of which is deemed to be included here.

The reader station 3 furthermore has an accumulator 19 and an externalpower supply connection 20 and energy source recognition means 21, theseenergy source recognition means 21 being connected to the accumulator 19and the external power supply connection 20, and being designed to emita supply voltage V to the station circuit 5, as well as an energy sourcerecognition signal ESS to the arranging means 9. In the present case,the energy source recognition means 21 are designed as electronicchange-over switches, wherein where an external energy source orexternal voltage source is present at the external power supplyconnection 20, this external voltage source is designed to supply thestation circuit 5 with energy or voltage, and an energy sourcerecognition signal ESS that represents this external voltage source isemitted; otherwise a switch-over to the accumulator 19 takes place andthe station circuit 5 is supplied with the aid of the accumulator 19,and an energy source recognition signal ESS that represents theaccumulator 19 is emitted.

In the present case, the data carrier 2 is a portion of a mobile phoneand contains the circuit 4, as already mentioned. The circuit 4 isdesigned as an integrated circuit and contains a micro-computer 22. Themicro-computer 22 contains a central processing unit 23 and storagemedia 24, this central processing unit 23 and storage media 24 workingtogether in a familiar manner.

With the aid of the central processing unit 23, command signalrecognition means 25 for recognizing a command signal COM that can betransmitted with the aid of the reader signal RS′ of the reader station3, and command/response command generators 26, and determination means27, and sequence controllers 28 are realized; we shall deal with themeans that are mentioned above and are realized with the centralprocessing unit 23 in greater detail below.

The circuit 4 also has an oscillator 29 for producing and emitting acarrier signal TS of the data carrier 2, and first switching elements 30and modulation elements 31 and detectors 32 for detecting the presenceof the received carrier signal RS, which carrier signal RS wastransmitted by the reader station 3 as reader signal RS′, anddemodulation elements 33 for demodulating the received carrier signalRS, and DC voltage generating means 34, and power supply change-overelements 35.

The data carrier 2 also has transmission means 36, these transmissionmeans 36 forming both transmitters and receivers, and which define thecommunication area, not shown, of the data carrier in the case oftransmission, which communication area of the data carrier includes thereader station 3. Also contained in the data carrier 2 is an accumulator37, this accumulator 37 being connected to the power supply change-overelements 35 and serving to supply energy or voltage to the circuit 4 inone communication mode, which will be dealt with in greater detailbelow.

The mobile phone and the PDA are designed as so-called “Near FieldCommunication” (NFC) devices for an NFC communication system. In thisNFC communication system, the mobile phone and the PDA are designed ascommunication partner appliances with equality of access, and both themobile phone and the PDA can assume the role of an initiator, whereinwhen the role of initiator has been assumed by one of the twocommunication partner appliances, the other communication partnerappliance respectively assumes the role of a target. Consequently in thepresent case, the functionality of the data carrier 2 and of the readerstation 3, described above, is included in each of the two NFC devices,wherein for each NFC device, all the components required for thefunction of the data carrier 2 and the reader station 3 are included orrealized jointly in an integrated circuit. It can be mentioned that allthese components can be contained in two separate circuits.

Each of the two NFC devices or each of the two facilities follows acommunication protocol for the role that has been assumed respectively,this communication protocol being stored in the respective storage mediaand being executed with the aid of the respective sequence controllers.In the present case, a communication protocol that is required for thefunction of the target is stored in a communication protocol storagearea 38 of the storage media 24 of the data carrier 2, and can beexecuted with the aid of the sequence controllers 28 of the data carrier2. Furthermore, a communication protocol that is required for thefunction of the initiator is stored in a communication protocol storagearea of the station storage media 8 of the reader station 3, and can beexecuted with the aid of the sequence controllers 14 of the readerstation 3. Each of the two NFC devices is envisaged to be able to workin an active communication mode or in a passive communication mode,wherein for the target in the case of the active communication mode, apower supply for the circuit 4 is provided that is independent of thecarrier signal RS, and in the case of the passive communication mode apower supply for the circuit 4 is provided that is dependent on thecarrier signal RS. Such an active and passive communication mode isdescribed for example in the published standard ECMA-340 of December2002 (at http://www.ecma.ch or http://www.ecma-international.org/),whose disclosure in this regard is included herewith by reference.

An advantageous use of such an NFC device is described below on thebasis of FIGS. 2 and 3.

Shown in FIG. 2 is an entry-monitoring communication system 39, whereinin the present case the data carrier 2 contained in the PDA and a readerstation 40 are shown. The reader station 40 and the data carrier 2 aredesigned for contact less communication according to a communicationprotocol defined in the standard ISO/IEC 14443, type A (MIFARE). It canbe mentioned that a different communication protocol can be appliedhere, for example according to the standard ISO/IEC 14443, type B,ISO/IEC 15693, ISO/IEC 18000. The reader station 40 containscommunication elements, not shown in further detail, for communicatingwith the device designed as a data carrier 2, these communicationelements being disclosed for example in the document US20030128124“Communication station for inventorizing transponders by means ofselectable memory areas of the transponders”, this disclosure beingincluded herewith the reference.

In the present case, the entry-monitoring communication system 39 servesto monitor entry to a subway. For this instance, the data carrier 2 hasentry authorization data, these entry authorization data being providedfor access to and therefore use of the subway. The reader station 40 hasa fixed electrical power supply and is operated in the passivecommunication mode. The term “passive communication mode” as applied tothe reader station 40 is chosen not because the reader station 40 issupplied from a remotely located energy source, but because in the caseof the passive communication mode of the reader station 40, the at leastone data carrier 2 that is in communication connection with the readerstation 40 is operated in its passive communication mode. In the presentcase, the PDA with the data carrier 2 located in it is brought into thecommunication area CA′ of the reader station 40 by the user of the PDA.In accordance with the passive communication mode, the reader station 40continuously transmits a reader signal RS, this reader signal RS beingreceived by the transmission means 36 of the data carrier 2, and beingtransmitted to the detectors 32 and the demodulation elements 33 and theDC voltage production means 34. The DC voltage production means 34 areconnected to the supply change-over elements 35 and are designed todeliver a supply voltage V in a familiar manner. In the present case,the supply change-over elements 35 are designed such that initially, thevoltage that can be delivered by the DC voltage production means 34serves to supply the circuit 4. In the present case, in the event thatthe carrier signal RS reader station 40 is present, the detectors 32transmit a carrier signal present signal PS to the determination means27. The demodulation elements 33 are designed for demodulating thereceived reader signal RS and for transmitting the command signals thathave been transmitted with the aid of the reader signal RS to thecommand signal recognition means 25. For example, in the present case aninventorizing command signal ICO is transmitted. The command signalrecognition means 25 are designed to transmit a command-end signal CESthat represents the end of the transmitted command signal to thedetermination means 27. The determination means 27 now establishwhether, after the occurrence of the command-end signal CES, at ameasurement point in time, the carrier signal present signal PS ispresent, wherein the determination means 27 transmit a first activationsignal AS1 when the carrier signal present signal PS is present andotherwise, i.e. when the carrier signal present signal PS is notpresent, they transmit a second activation signal AS2. In the presentcase of the reader station 40 that is set according to the passivecommunication mode, after the command-end signal CES has beentransmitted, the carrier signal present signal PS is present and thedetermination means 27 transmit the first activation signal AS1 to theswitching elements 30 and the supply change-over elements 35. The supplychange-over elements 35 are designed, on the basis of the firstactivation signal AS1, to switch over to the voltage for supplying thecircuit 4 that is to be delivered by the DC voltage production means 34.The circuit 4 is thus switched into the passive communication mode,wherein an electrical power supply applies that depends on the readersignal RS, and advantageously the device's own limited power supplyprovided by the accumulator 37 is conserved.

A further advantageous use of such an NFC device is now described on thebasis of FIG. 3, in which FIG. 3 a communication system 39 b is shown.In the present case it is assumed that the user of the PDA in the subwaybecomes aware of an advertising poster for an event, further referred toas poster for short. The poster has a tag 41 as shown in FIG. 3, thistag 41 containing event information about an event advertised on theposter and being designed for communicating in a passive communicationmode. Such tags are well known in specialist circles, which is why theywill not be elucidated further here. Also shown in FIG. 3 is thatportion of the PDA which, according to FIG. 1, is designated as a readerstation 3. In the present case, the reader station 3 is used for readingout the event information from the tag 41. Via the PDA's input means,not shown in further detail here, such as a keyboard in the presentcase, the reader station 3 is activated as an initiator, wherein onaccount of the circumstances the accumulator 19 is activated to providethe power supply for the circuit 5. The PDA or the reader station 3 isnow brought into the vicinity of the poster, so that the tag 41 comesinto the communication area CA of the reader station 3. The readerstation 3 according to FIG. 3 also has response signal detectors 42,these response signal detectors 42 being realized with the aid of thecentral processing unit 7. The response signal detectors 42 areconnected to the reception signal processing means 13, and are providedfor the detection of a response signal TS that is transmitted by thefurther communication partner appliance; when one is detected by theresponse signal detectors 42, a switch-over signal US can be generated,which switch-over signal US can be transmitted to the fixing means 9.Here, the fixing means 9 are designed automatically to set thecommunication mode depending on the switch-over signal US that has beengenerated.

If, as in the present case, the reader station 3 starts according to aprotocol for the active communication mode, the tag 41 will not emit aresponse signal TS and consequently no response signal TS will bereceived in the reader station 3 and processed. Subsequently, with theaid of the response signal detectors 42, the switch-over signal US isgenerated and transmitted to the arranging means 9, whereupon the readerstation 3 switches into the passive communication mode that isappropriate for communicating with the tag 41. The event information cannow be read out in the customary manner from the tag 41, and then storedin the station storage media 8 for further use.

Such further use is now described on the basis of FIG. 1. In the presentcase it is assumed that the user of the PDA wishes to draw a friend'sattention to the aforementioned event and wishes to convey the eventinformation to that friend. This is to take place by means of theaforementioned mobile phone. For this, the event information stored inthe PDA or station storage media 8 of the reader station 3 istransmitted to the mobile phone. The PDA or the reader station 3 can, asmentioned above, be activated by means of input means and assumes therole of initiator. The mobile phone with the data carrier 2 containedtherein is brought into the communication area CA. As already mentionedin connection with FIG. 2, in the data carrier 2 the supply change-overelements 35 are designed such that initially, the voltage that can bedelivered by the DC voltage production means 34 serves to supply thecircuit 4. On account of the power supply by the accumulator 37, thereader station 3 is first of all operated in the active communicationmode. The subsequent communication sequence is now described on thebasis of FIG. 4.

As is shown in FIG. 4, from a first point in time t1 onwards, thecarrier signal RS is generated and is then transmitted as a readersignal RS′. From a second time point t2 to a third time point t3, in thegenerators 10 of the reader station 3 a command signal COM is generatedand is emitted as a modulated signal with the carrier signal RS. Thefirst control elements 11 transmit a command-end signal CES of thereader station 3 that represents the end of the generated command signalCOM to the second control elements 12, whereupon the second controlelements 12 initiate the situation that after a time period TPR afterthe occurrence of each command-end signal, the carrier signal RS isswitched off by the command-end signal CES of the reader station 3 inthe production means 15, or is no longer generated, and consequently noreader signal RS′ is transmitted to the data carrier 2. The time periodTPR corresponds in the present case to a period duration of 30oscillations of the carrier signal or reader signal RS. It can bementioned that the time period TPR can be greater, for example 60 or 90oscillations of the carrier signal, or smaller, for example just 10 or20 oscillations of the carrier signal. What is important here is thatthe detectors 32 have sufficient time to be able safely and reliably torecognize whether the carrier signal RS′ is present or no longer presentor switched off.

The switching off of the carrier signal RS takes place at a fourth pointin time t4 in accordance with FIG. 4. It can be mentioned that interruptelements for interrupting the transmission of the reader signal RS′ canbe arranged between the modulation elements 16 and the transmissionmeans 18, and these interrupt elements can then be activated by thesecond control elements 12 for interruption.

As has already been mentioned, the detectors 32 of the data carrier 2are designed to detect the presence of the received carrier signal RS.The detectors 32 are furthermore designed to emit or transmit a carriersignal present signal PS in the event that the carrier signal RS ispresent, and otherwise to emit or transmit a carrier signal not-presentsignal NPS. In the present case, in FIG. 4 the time dependent behaviorof the carrier signal present signal PS is shown, wherein such a carriersignal present signal PS is no longer transmitted from the fourth timepoint t4 onwards. Furthermore, the command signal recognition means 25of the data carrier 2 are designed to recognize a command signal thatcan be transmitted with the aid of the carrier signal RS, and to emit acommand-end signal CES that represents the end of the transmittedcommand signal. Shown in FIG. 4 is the time progression for thecommand-end signal CES of the data carrier 2 for the present case,wherein from the third time point t3 onwards, i.e. after the end of thecommand signal COM transmitted by the reader station 3, the command-endsignal CES is shown as a short pulse. In the determination means 27,triggered by the command-end signal CES, after a time period DTP it isestablished whether, after the occurrence of the command-end signal CES,at a measurement point in time, as in this case after the expired timeperiod DTP at a fifth point in time t5, the carrier signal presentsignal PS is present. In the present case the time period DTP lasts for60 oscillations or periods of the carrier signal RS. It can be mentionedthat the time period DRP can be of a different duration, for examplethree or four times the duration of the time period TPR. According tothe present circumstances, the determination means 27 transmit thesecond activation signal AS2, since at the fifth point in time t5 nocarrier signal present signal PS is present. Subsequently, with the aidof the second activation signal AS2 the circuit 4 is brought into thesecond communication mode with the aid of the activators, i.e. in thepresent case into the active communication mode, wherein for this thesupply change-over elements 35 are controlled such that the power supplyfor the circuit 4 is provided by the accumulator 37, and wherein thefirst switching elements 30 are controlled such that a carrier signalfor generating the data carrier signal TS can be transmitted by theoscillator 29 in a familiar manner to the modulation elements 31 of thedata carrier 2.

It can be mentioned that instead of the aforementioned PDA, theaforementioned mobile phone can be used to read out such a tag 41,wherein the event information can then be transmitted to the PDA, and inthe course of this the mobile phone can take on the role of the readerstation 3.

It should furthermore be mentioned that instead of the mobile phone orPDA, other devices can be designed as NFC devices, for example a laptop,a watch, a digital camera, a camcorder and much else besides. Thus forexample it can be the case that with such a watch designed as an NFC,the type of event information mentioned above can be polled andsubsequently this event information can be conveyed to the laptop, forexample for the purpose of managing appointments. The laptop canoptionally be connected to a power supply mains network or operatedindependently of the mains supply, with an accumulator. Depending on theelectricity or power supply situation of the laptop, correspondingcommunication can be initiated in the passive communication mode oractive communication mode, as has been explained above.

It should furthermore be mentioned that the reader signal RS′ and thedata carrier signal TS can lie in another frequency range, for exampleat a frequency of 125 kHz.

It should furthermore be mentioned that influencing means forinfluencing a signal strength of the carrier signal RS depending on theset communication mode can be provided in the reader station 3 and/or inthe data carrier 2. Thus the influencing means can for example bedesigned such that in the active communication mode, the reader signalRS′ is transmitted with a low field strength, through which the device'sown power supply that is used in the case of the active communicationmode can be conserved.

What is claimed is:
 1. A communication partner appliance comprising: atransmitter configured to transmit a near-field communication (NFC)command signal to another communication partner appliance according toan active communication mode, wherein the command signal includes arequest for data from the other communication partner appliance; and aprocessor coupled to the generator and the transmitter, wherein theprocessor is configured to switch from the active communication mode toa passive communication mode in response to a determination that theresponse signal is not received from the other communication partnerappliance.
 2. The communication partner appliance of claim 1, whereinthe generator is configured in the active communication mode to generatethe carrier signal only during the transmission of the command signal tothe other communication partner appliance.
 3. The communication partnerappliance of claim 2, wherein the processor is further configured toinfluence a signal strength of a carrier signal used for thetransmission of the command signal in the active communication mode. 4.The communication partner appliance of claim 1, wherein the generator isconfigured in the passive communication mode to generate the carriersignal during and after the transmission of the command signal to theother communication partner appliance.